Apparatus for forming templates



July 6, 1943.

F. A. FAULHAB ER 2,323,528 APPARATUS FOR FORMING TEMPLATES.

Fil ed June 4, 1941 2 Sheets-Sheet l July 6, 1943. F, A, FAULHA ER 2,323,528

.APPARATUS FOR FORMING TEMPLATES Filed Jun 4, 1941 2 Sheets-Sheet 2 7 FIG.2.

. I INVENTOR s Fig.5. BY mgaosmcmmuwman AM fi A TTORNEYS by templates.

Patented July 6, 1943 UNITED STATES parser orrics APPARATUS non FORMING 'rnivirre'rns Frederick A. Fauihaber, Detroit, Mich, assignor to The Gear Grinding Machine Company, Hamtramck, Mich, a corporation of Michigan Application June 4, 1941, Serial No. 396,630

6 Claims. (01. 90-13) lChe invention relates to the forming of templates of an exactly predetermined curvilinear contour and has more particular reference to the forming of templates of involute contour such as used in connection with the form grinding of gear Wheels. It is the object of the invention to obtain greater accuracy in the product and also to facilitate and expedite the manufacture of the same.

With these objects in view, the invention consists in the construction as hereinafter set forth.

In the drawings:

Fig. l is a plan view of the apparatus, showing the means of conforming the flexible bar to an arcuate curve;

Fig. 2 is a perspective view illustrating the means for cutting the involute curve in the template;

Fig. 3 is a vertical cross section through the arcuate bar and supporting and positioning means therefor;

Fig. i is a horizontal section showing the attachment between the flexible band and the milling tool;

Fig. 5 is a section on line 5-.5 of Fig. l; and

6 is a plan view illustrating the means of testing the accuracy of the template.

Trimming mechanisms used in connection with form grinding machines are usually controlled Such templates are of a contour exactly corresponding to the cross sectional contour of the grinder wheel, but usually upon a magnified scale. The diamond trimmer for the grinder wheel is controlled in its movement by the template, and the scale or the work reduced to proper size through the medium of a pantograph or other reduction mechanism. It is obvious that the accuracy of the finished work is dependent upon the accuracy of the template contour, so that great care must be taken in the forming of the latter.

As is well understood, an involute curve may be developed by the travel of a point in a flexible band which is unwrapped from an arc of a circle. The form of this curve is therefore dependent--- First, upon the radius of the are, or what is commonly known as the base circle;

Second, on the accuracy of the are or the constancy of its radius; and

Third, 0n the distance from the base circle of the segment of the curve which is used.

3 'In view of the conditions just described, my

improved template-forming apparatus, generally described, comprises:

First, a supporting table on which the template blank is secured;

Second, a flexible member and means for conforming the same to an arcuate curve of predetermined radius;

Third, means for rigidly securing said arouate member on said table. in predetermined relation to the template blank;

Fourth, a blank cutter; and

Fifth, a flexible connection between said blank cutter and arcuate member, permitting of wrapping about the latter and guiding the movement of said cutter in operative relation to the blank. This will cut the blank to the desired involute contour. It is, however, essential, as above stated, that the 'arcua'te member should be held rigid in form and position during the performance of the work, as otherwise thedeveloped contour of the template will not be true. It is equally important that the flexible membershould first be freely conformable to the selected arcuate curve and that means should be provided for thus conforming it. I have, therefore devised an apparatus in which the flexible member is pivotally connected at spaced points therein with supporting blocks slidable upon the table. I have further provided a radius arm adapted to swing about a pivotal support, with a finger for contacting with said flexible member to shift the same and its supporting blocks into conformity to the desired arcuate curve. Both the supportin pivot and the finger are adjustable, so that any desired length of radius may be selected. For holding the arcuate member rigid during the performance of the work, I preferably employ electromagnetic mean for locking the supporting blocks in fixed relation to the table.

More in detail and as illustrated in the drawings, A is the table which is formed by a plate of magnetic metal suchas soft iron or steel. Bis the template blank which is positioned on a portion of the table and rigidly secured thereto by suitable means such as screws C. D is a rail connected to the table and extending outward therefrom to a suitable supporting standard E. F is' a block adjustable upon the railD and secured thereto in different positions of adjustment by one or more clamps G. This block is provided with a pivot H for engaging a pivot bearing at the end of a radius arm I extending over the table and spaced a short distance above the same. This radius arm has adjustably mounted thereon a depending finger J secured in different positions of adjustment by a clamping screw K.

L is a flexible bar or band, preferably formed of resilient metal. This bar is supported slightly above the table by a series of blocks M, each of which has a forwardly extending arm M pivotally attached to the bar. This attachment is preferably formed by a loop or eye L secured to one side of the bar, preferably by welding, and extending rearward therefrom into a slot M at the forward end of the arm M and engaging a pivot M This permits flexing of the bar without restraint, while at the same time supporting it at spaced points in its length. Thus, the bar may be conformed to an arcuate curve by contacting the finger J therewith and swinging the radius arm I about the pivot H, the blocks M being freely movable on the table A.

To look the blocks to the table after the proper positioning of the same thereon and the conforming of the bar to the desired arcuate curve, I preferably employ electromagnetic means. To this end, each of the blocks is provided with an electromagnetic unit, together with energizing means controlled by a switch M so that when this switch is closed, the block will be magnetically held to the table. The electromagnetic unit is not my invention and therefore need not be described in further detail. I do, however, preferably provide the blocks M with upwardly projecting handles M for conveniently adjusting the same upon the table.

For cutting the blank, I preferably employ a portable milling tool, which is electrically driven. This tool N, which is not my invention and may be of any suitable construction, is provided with a base N having a cutaway portion N in which the rotary milling cutter and its shaft are located. is a yoke member secured to the base N by a threaded shank O' and adjustable nut 0 The outer end of this yoke is secured to a flexible band P which is in alignment with the axis of the cutter and extends to the arcuate member L, being attached thereto by a clamp P. The band P is adapted to wrap about the arcuate member L and in so doing restrains the movement of the tool N to an involute path. Thus, the operator may manually adjust the tool N, causing the rotary milling cutter N to fashion the blank B to the desired involute contour. The blank is supported slightly above the table, by resting upon pads B, so that the cutter will not contact with the table.

From the description above given, it will be understood that any desired involute curve contour may be imparted to the blank First, by adjusting the length of the radius arm I between the pivot H and the finger J, to correspond to the arc of the proper base circle; and

Second, by swinging this radius arm with the finger J contacting with the flexible bar L and traveling along the same.

The blocks M may be simultaneously adjusted bymeans of their handles M and after each block is properly positioned, th switch M is operated to electromagnetically lock the block in fixed position on the table. After the bar L has been'conformed to the arc traced by the finger J and all of the blocks M have been locked in position, the flexible band P is clamped at one point to the member L and with the tool N in operative relation to the blank B. The operator may then move the tool N as before described, thereby cutting the blank to the involute curve.

If desired, the accuracy of the template may be tested by attaching a gauge Q to the free end of the band P and moving the same about the fashioned contour of the blank.

The finger J preferably comprises the clamping bracket J and the member J pivotally attached thereto and adjustably clamped by a screw J The member J at its lower end has a portion J for contacting with the flexible bar L, and by angularly adjusting this member on its pivot, said portion J can be placed in full contact with the flexible bar L.

What I claim as my invention is:

1. An apparatus for forming templates comprising a table, means for positioning and securing a template blank thereon, a flexible bar, means for conforming said bar to an arcuate curve of predetermined radius, means for rigidly securing said arcuate bar to said table in predetermined relation to said template blank, a blank cutter, and a flexible band connecting said cutter to said rigid arcuate bar to permit of wrapping about the latter with said cutter moving in operative relation to said blank to fashion the same to an involute curve.

2. An apparatus for forming templates comprising a table, means for positioning and securing a template blank thereon, a flexible bar freel movable on said table, means for conforming said bar to an arcuate curve of predetermined radius, means for electromagnetically locking said arcuate bar rigidly to said table in predetermined relation to said template blank, a blank cutter, and a flexible band connecting said outter to said arcuate bar permitting of wrapping about the latter and determining the path of movement of said cutter in relation to said blank to fashion the same to an involute curve.

3. In an apparatus for forming templates, the combination with a table and means for securing a template blank thereon, of a flexible bar, a plurality of blocks resting on said table to be freely movable thereon and pivotally attached to said bar at spaced point therein, means for shifting said blocks and conforming said bar to an arcuate curve of predetermined radius, means for locking said blocks rigidly to said table and thereby holding said arcuate bar rigid, a blank cutter, and a flexible band connecting said outter with said arcuate bar permitting of wrapping about the latter and thereby determining the path of movement of said cutter in relation to the blank.

4. In an apparatus for forming templates, the combination of a table formed of magnetic metal, means for securing a template blank thereon, a flexible bar, a plurality of electromagnetic units freely slidably supported on said table and pivotally connected to said bar at spaced points therein, means for progressively conforming said bar to an arcuate curve of predetermined radius, means for successively energizing said electromagnetic units to hold the same rigidly positioned on said table and to thereby maintain said arcuate bar in rigid relation to said blank, a blank cutter, and a flexible band connecting said cutter with said arcuate bar permitting of wrapping about the latter and thereby determining the path of movement of said cutter in relation to the blank.

5. In an apparatus for forming templates, the combination with a table, of a rail secured to said table and projecting outward therefrom substantially in the plan thereof, a pivot member adjustably secured to said rail, a radium arm above said table having one end engaging said pivot, a finger adjustably secured to said radius arm and projecting downward therefrom toward said table, a flexible bar, a plurality of blocks pivotally attached to said bar at spaced points therein and resting on said table, said blocks and bar being freely adjustable on said table to maintain contact between said bar and said finger during the swinging of said radius arm on its pivot and to thereby conform said bar to an arouate curve of predetermined radius, means for rigidly locking said blocks to said table to hold said bar in its arcuate form, a blank cutter, and a flexible band connecting said cutter with said arcuate bar permitting of wrapping about the latter and thereby determining the path of movement of said cutter in relation to the blank.

6. In an apparatus for forming templates, the combination with a table, of a rail secured to said table and projecting outward therefrom substantially in the plane thereof, a pivot member adjustably secured to said rail, a radius arm above said table having one end engaging said pivot, a flnger adjustably secured to said radius arm and projecting downward therefrom toward said table, a flexible, resilient bar, a plurality of normally deenergized electromagnetic units pivotally attached to said bar at spaced points therein, and resting on said table, said units and bar being freely adjustable on said table to maintain contact between said bar and said finger during the swinging of said radius arm on its pivot, and to thereby conform said bar to an arcuate curve of predetermined radius, means for energizing said units to rigidly lock the same to said table and to hold said bar in its arcuate form, a template blank secured to said table, a blank cutter, a flexible band connected at one end to said blank cutter, and also connected to said flexible bar, permitting of wrapping about the same, whereby said cutter may be used to fashion said blank to an involute curve.

FREDERICK A. FAULHABER. 

